1. Field of the Invention
The present invention generally relates to a battery charging system for electric vehicles, and more particularly to an integration of main battery charger components and auxiliary battery charger components for common use.
2. Description of the Related Art
As prior art, the Japanese Unexamined Utility Model Publication No. 63-33337 discloses a technique in which a charger is dedicated to a main battery for driving a vehicle and to an auxiliary battery for driving auxiliary type loads are. This technique aims to reduce the size, weight and cost of the chargers by using a common DC/AC converter and transformer but at the cost of providing a change-over switch selectively switching the main battery charger and the auxiliary charger on the main battery side.
However, in the battery charging system disclosed in the above publication, two sets of large-capacity change-over switches to meet the large current flowing into the main battery are required on the main battery side, and this poses a problem in that the frame of the battery charging system must then be enlarged to accommodate the two sets of large-capacity change-over switches.